This invention relates generally to electronic solid state devices and more particularly, to apparatus for dissipating heat generated by such devices.
As advances are made in the electronics industry with more functions provided in smaller architecture, the efficient removal of heat becomes increasingly important. Solid state devices, such as microprocessors and the like, generate a great deal of heat during operation which must be removed to prevent adverse effects on operation of the system in which the solid state device is used and even self-destruction of the device or destruction of near-by components.
It is known to thermally couple heat sinks with such devices in order to dissipate heat generated by the devices and, consequently, lower the temperature of the devices to safe limits. One example of such a heat sink is shown and described in U.S. Pat. No. 4,745,456. In that patent, a finned heat sink comprising a central post having a plurality of spaced fins extending radially from the post is secured to an electronic device package by means of a clip which attaches to a latch mechanism on a frame in which the device package is held and which releasably grips the heat sink and urges it into engagement with the device package. This structure, while effective when the clamping force biases the heat sink into firm engagement with the electronic device package, tends to be inconsistent as the semi-conductor heats up and, at elevated temperatures, the force biasing the heat sink against the device package can decrease making the thermal path less efficient. In fact, apparently due to differences in the thermal expansion of the several parts, the thermal coupling between the heat sink and the device package can be significantly diminished caused by a slight tilting of the heat sink surface to break the plane to plane contact of the heat sink core with the top surface of the electronic device package. Even when thermal grease is placed between the heat sink and the device package, it is found that thermal coupling can be significantly reduced with the result that the device package overheats and causes deleterious operational effects.
Heat sinks have also been permanently bonded to the electronic device package to provide an efficient thermal coupling between the two components; however, over time the bond tends to break thereby adversely affecting the thermal path between the heat sink and the device package.
Another approach to preventing overheating has been to mount a small fan on the heat sink to increase thermal dissipation of the heat sink. While this can be very effective in maintaining the temperature of the device package to acceptable levels, it is not only costly if operation of the fan is interrupted due to some malfunction, but the device will be ineffective to prevent unwanted temperature rise.
It is an object of the present invention to provide a heat sink assembly for removing heat from an electronic device which is reliable yet inexpensive, one which obviates the limitations of the prior art mentioned above.